The present invention relates to an electrical connector for two rows of contacts, particularly for contacts at the interface between a mother board and a daughter board.
Circuit boards are commonly interconnected by providing connectors on a mother board which each receive the edge of a daughter board. The connectors have rows of spring contacts therein which electrically interconnect circuit traces on the daughter board to circuit traces on the mother board. The connectors are commonly designed as zero insertion force or "ZIF" connectors, the daughter board being inserted in a recess having spring contacts on either side thereof. A cam key is then moved to bring contact pressure to bear against the contact pads on the daughter board. This is accomplished by removing a key which deflected the contacts away from the daughter borad, or by rotating a key to reverse the deflection. The connection to the mother board is frequently via pins in plated through holes, which usually require soldering after insertion of pins.
Surface mount capability is becoming increasingly desirable from a manufacturing standpoint, insofar as pins are eliminated. Thus, a connector having contacts which can wipe against contact pads on both boards is needed; wiping is desirable as it removes surface impurities to improve electrical contact. The trend of increasing miniaturization makes a high contact density also desirable.
U.S. Pat. No. 3,715,706 discloses an electrical connector for interconnecting first and second substantially parallel rows of uniformly spaced surface contacts on respective first and second surfaces at substantially right angles to each other. The connector comprises an elongate dielectric housing having a first face for mounting against the first surface over said first row of surface contacts and a second face for mounting against the second surface over the second row of surface contacts, the second face being substantially perpendicular to the first face. The housing has a plurality of parallel planar recesses therein, each recess extending into the first face and the second face and continuously therebetween, the recesses being spaced as the surface contacts and defining parallel planar barriers therebetween. The connector further comprises a plurality of contacts in respective recesses, each contact having first and second contact surfaces on the periphery thereof at respective first and second faces of the housing.
The described connector utilizes contacts formed from a single long piece of spring metal to form contact surfaces integral with a spring. The connector is not a "ZIF" connector insofar as contact surfaces are urged toward respective housing faces at all times, and contact forces are limited. Further, the current path between the surfaces, which are usually on circuit boards, is much longer than the direct distance between surfaces.